Three Hong Kong activists will have to wait to learn the outcome of their final appeal Tuesday to overturn prison sentences for their roles in sparking 2014's massive pro-democracy protests in the semiautonomous Chinese city.

Judges at Hong Kong's top court said they would issue their decision at a later, unspecified date following the appeal hearing for Joshua Wong, Nathan Law and Alex Chow against the sentences of up to eight months. Bail for the three was extended.

The three were initially let off with suspended or community service sentences after they were convicted of taking part in or inciting an unlawful assembly by storming a courtyard at government headquarters to kick-off the protests.

But the case sparked controversy when the justice secretary requested a sentencing review that resulted in stiffer sentences, raising concerns about rule of law and fears that the city's Beijing-backed government is tightening up on dissent.

The trio's lawyers said the lower court overstepped its boundaries and put too much emphasis on the need for deterrence in handing down the revised harsher sentence.

"Laying down a heavy sentence will have a deterrent effect, but a balance has to be held between a deterrent and stifling young idealistic people," Law's lawyer, Robert Pang, told the judges.